Portable power-operated rotary taper cutting device



Dec., 13, 1949 w. H. GRAssr-:R

PORTABLE POWER OPERATED ROTARY TAPER CUTTING DEVICE 2 Sheets-Sheet 1 Filed Jan. 25, 1946 FIG. 2.

FIG. 5. 3o

38 INVENTOR.

WALTER HGRASSER ATTCI R N EYB Dec. 13, 1949 w. H. GRASSI-:R 2,491,105

PORTABLE PowER oPEEA'rED ROTARY TAPEE CUTTING DEVICE Filed Jan. 25, 1946 2 Sheets-Sheet 2 F'IG. 4.

2e 22 l 56 54 2 le FIG. 5.

INVENTQR. WALTER H. GRASSER m mfg/Mw@ Patented Dec. 13, 1949 OFFICE PORTABLE POWER-OPERATED ROTARY TAPER CUTTING DEVICE Walter H. Grasser, Wichita, Kans.

Application January 25, 1946, Serial No. 643,425

l Claim.

This invention relates to a portable jointer which is especially adapted to be used in connection with airplane repairs and other similar uses.

The device will be used extensively in connection with repairs to the wood spars of airplane wings which have been damaged. The Civil Aeronautics Administration governing approved repairs to all certified aircraft, states that wood spars that have been broken or damaged may be repaired by splicing and gluing in a new spar section.

. This new spar section may be either from the break inboard or from the break outboard. The important point is, that the taper of the splice be a minimum of ten to one, or for a one inch thick spar the taper cut Will be ten inches long.

Obviously, that portion of the spar which remains in the Wing will have to vbe tapered by hand methods which usually take the better part of a day. First the wing must be removed so as not to have to work overhead. The ragged portion at the break must then be cut off and all the ribs removed from the portion to be ren placed. Then by means of saw, plane and scraper the ten to one taper is made as accurately as possible by hand. No sandpaper can be used since it is in conict with good gluing practice.

The mating taper is then made on the mating portion of the replacement spar section. This is either done in the same manner by hand in the small shop, or by trial and error on a jointer, since the taper angle of the cut will have to be such that when in contact with the mating part, the spar will be perfectly straight. It is quite a lengthy process to shape by hand, the mating parts of a spar splice as well as a diflicult one. An operation of this sort can only be handled by highly skilled workmen.

It is an object of the invention therefore to provide a device Which will quickly and accurately cut a smooth accurate ten to one taper on both mating portions of a spar splice.

Another object of the invention is to provide a device that is self-contained, portable, xed in adjustment, requires no prior figuring or setting, cannot get out of adjustment, presents no maintenance problem and has low operating and initial cost.

The device will prove an asset in every airplane repair shop. It can be operated by other than mechanics or skilled operators, since it can be installed and operated by the most inexperienced workman with the same accurate precise results. Since the device can be operated in any position it is not necessary to remove the wing from the aircraft to make the splice.

With the foregoing and other objects and advantages in View the invention consists of the novel details of construction, arrangement and combination of parts more fully hereinafter described, claimed and illustrated in the accompanying drawings in which:

Figure 1 is a top plan View of an embodiment` of the invention. Y

Figure 2 is a side view thereof.

Figure 3 is a sectional View on the line 3-3 of Figure 1.

Figure 4 is a sectional view on the line 4 -4 of Figure 1, and

Figure 5 is a sectional view on the line 5--5 of Figure 2.

Referring more in detail to the drawings-'the reference numeral I0 designates the jointer which comprises the three major parts consisting of the sliding carriage I2 the vcarriage support frame I4 and the base plate I6.

The base plate I6 is rectangular in shape and made of steel or any other suitable material. At one end of the base plate I 6 there are provided oppositely positioned upright lugs I8 which are formed on the longitudinal edge of the base and are apertured at the upper end thereof. The opposite end of the base plate I6 is apertured adjacent the opposite corners thereof to receive studs 20, having cam action, levers 22 pivotally mounted thereon. The studs 20 extend through the base plate I 6 to be received in the clamping bar 24 which extends transversely of the base plate I6. The studs have a shrink nt in the clamping bar and the studs are threaded to receive the pivot pin 26 of the levers 22.

Spaced from the clamping bar 24 and formed on the longitudinal edge of the base plate I6 are a second pair of opposed upright lugs 28 which are parallel to but of a greater height than the lugs I8, the lugs 28 are also apertured at the upper end thereof.

The base plate can have lightening holes bored through its entire surface or might be die cast from Zamac or any other suitable metal in the interests of weight saving.

Formed on the base plate I6 intermediate the clamping bar 24 and the upright lug 28 on the left longitudinal edge of the plate is the upright guide lug 29 which is parallel to the lugs on the left side and of approximately the same height as the upright lug 28, as many clamping bars 3 and guide lugs may be used as desired but the guide lugs may vary in height as desired.

The carriage support frame I4, comprises the opposed channel shaped sides 30 and the end strips 32 joined to the ends of the sides by bolts 24 and 34. To further strengthen the sides 30, strips of metal 36 of a larger size are secured to the sides 30 by bolts 38. The bolts 24 and 34 pass througlithe-sides 30 and strips 36 to join the ends thereto in unit assembly. Thus the carriage support is easy to construct, is relatively inexpensive and is rigid.

The carriage support frame I4 is secured to the upright lugs by means of Allenlscrewsii which pass through apertures spacedfrom the outer ends of the frame.

. The sliding carriage I2 consistsof a steel plate 42 extending across the base plate I6 and received in the sides 30 thus there is provided'a support as well as a trackfor the plate to follow.

The steel'endstrips 32 secured in the channelledf sides 30 serve as limiting stopsfor the travel of the'plate 42 in thesides 30 thus the'plate can be moved 4from one end of the frame I4 to the other limited in its movement only at the extreme endsthereof.

Formed on the steel plate 42 in spaced relationto the ends thereof are the upright rotor supports 44; Supports are formed on the plate so that the sides of the supports contact for sliding motion, the sides 30 ofthe frame I4. The rotor is provided with a shaft' 48 which is journalled in ball bearing race 49 mounted in the supports 44 and the rotor is'provided with three angularly related and relatively spaced cutter blades 50 or a rotor with a spiral cutter'may be used and the plate is cut-out at 5I to permit the cutter blades 50 toextend therethrough for `Contact with work placedon the base plate I6. The right end of the shaft 48 may be provided with a tang 52V for'engagement'with a slot in the drive shaftof an electric motor, not shown which is mounted on the right side of' the sliding carriage I2. A sheet metal guard over the rotor can also be connected to -the'rotor supports' 44Y forv safety. The sliding carriage as well as the base plate may also be die cast with a View of 'saving weight, and the guide lugs previously described serve to alignthe spar on the jointer.

Withthe carriage support frame bolted tothe base the lugs are so arranged in height that the frame assumes a six degree angle between the frame and basev and since this angle is fixed it automatically maintains a ten to one setting at all times. If a wood backing plate is used underl the spar when it is cut the taper can be continued into the backing plate to form a feather edge on the spar.

Since the six degree angle is xed to give aten to`one taper cut atv al1 times, spars of various thicknesses are accommodated by the deviceand the scarf cut in the spar will vary in length but still remain at a six degree angle.

When an airplane having a broken front spar is to be repaired and the break is better thanthe half way portion outboard from the root rib, the wing Vneed not be removed from the airplane. The covering the wingis removed from the break outboard, The ribs are removed'from the break outboard, brace wires are removed and the ragged edges' on the broken front spar are sawed straight. An approximate ten to one scarf is laid out and 4 roughly sawed through. If the spar is one inch thick by six inches wide a wood strip approximately two and one half inches in width is placed along the edge of the spar so as to bring the spar approximately in the center of the base plate, and rotor. The device is placed on the spar a backing plate is inserted between the spar and base plate and the clamps brought into contact with the'spar. The pinsv ofthe cam levers are threaded upwardly till contact is made with the bottom of the base plate at which time the levers are pressed against the bottom of the base plate, the cam action thereof giving a rm grip on the clamps. Then with the backing plate 54 in place under the spar 56 as shown in Figure 4 and the spar is centered the carriage is moved to the highest point in the support frame and the motor started and by pushing it downward against the spar the ten to one taperis cut and extending into the backing plate forms a feather edge on the spar.

The-piece of lumber for the remainder of'the spar can be tapered on a nearby bench by this same device and the tapers being fixed they will perfectly match and form an accurate scarf.

It is believed that the operation and construction of the device will be apparent to those skilled in the art and it is to be understood that changes in the detailsrof construction, arrangement andi combination of parts may be resorted to with-v out departing from the spirit of the invention andi the scope of the appended claim.

Having thus described the invention what is claimed as new and desired tol be'secured by Letters Patent is A deviceV of the character described, com-- prising a rectangular shaped base plate, an upf standing lug formed at one end of each of-the longitudinal edges of said base plate, an upstanding lug formed on each of the longitudinal? edges of said base plate intermediate the ends of said base plate, a carriage support fixed t'osaid lugs, said carriage support having inwardly facing channel sides, the lugs spaced inwardly off' the ends of said base plate being of a height to give said carriage an inclination with relation-to said base, a movable carriage mounted in the channelled sides ofv said carriage support, up'- standing lugs on said movable carriage, avrotary cutter mounted on a shaft journalled in said' lugs, means in the channelled sides of saidcarriage support to limit the movement of said' movable carriage, a guide lug on one longitudinaly edge of said base adjacent the other end thereof, and clamping means on theend of therbase adjacent the guide lug for holding the work on said base that is adapted to be cut by the rotary cutter on said movable carriage.

WALTER H. GRASSER.

REFERENCES CITED The following references are of record'in the le of this patent:

UNITED STATES PATENTS Number Name Date 169,414 Carmany Nov. 2', 1875'I 1,115,995 Willson Nov. 3, 1914i 1,306,249 Cobb et al. June 10, 1919- 1,580,155 Niestradt A'pr.' 13,11926 1,800,521 Girrbach Apr. 14, 1931" 

